What Is Glycerin? | Glycerol

Cold Process Soapmakers have it down to a litany. When asked why their soap is better than store-bought, they say (among other things), “Because of the natural glycerin. Glycerin is a humectant, meaning it attracts moisture to your skin. Glycerin is a natural by-product of the soapmaking process and while commercial manufacturers remove the glycerin for use in their more profitable lotions and creams, handcrafted soap retains glycerin in each and every bar.”

Melt and Pour Soapmakers have a similar line, “Commercial soaps remove the glycerin for use in more profit producing lotions and creams”, my soap has extra glycerin added to it. This helps make it clear, and also makes it a lot more moisturizing.

But what is glycerin, really?

Glycerin is a neutral, sweet-tasting, colorless, thick liquid which freezes to a gummy paste and which has a high boiling point. Glycerin can be dissolved into water or alcohol, but not oils. On the other hand, many things will dissolve into glycerin easier than they do into water or alcohol. So it is a good solvent.

Glycerin is also highly “hygroscopic” which means that it absorbs water from the air. Example: if you left a bottle of pure glycerin exposed to air in your kitchen, it would take moisture from the air and eventually, it would become 80 per glycerin and 20 percent water.

Because of this hygroscopic quality, pure, 100 percent glycerin placed on the tongue may raise a blister, since it is dehydrating. Diluted with water, however, it will soften your skin. (Note: While people say this softening is the result of the glycerin attracting moisture to your skin, there is heated debate as to whether or not the glycerin has some other properties all its own which are helpful to the skin. Summed up, the current thinking is “We know glycerin softens the skin. Some people think its because it attracts moisture, but there could be other reasons.”)

Where does glycerin come from?

Up until 1889, people didn’t know how to recover glycerine from the soapmaking process, so commercially produced glycerin mostly came from the candlemaking industry (remember, back then candles were made from animal fats).

In 1889, a viable way to separate the glycerin out of the soap was finally implemented. Since the number one use of glycerin was to make nitroglycerin, which was used to make dynamite, making soap suddenly became a lot more profitable! I have an untested theory that you could trace the roots of most big soapmakers (and the “fall” of the small, local soapmaker) to about this time in history.

The process of removing the glycerin from the soap is fairly complicated (and of course, there are a lot of variations on the theme). In the most simplest terms: you make soap out of fats and lye. The fats already contain glycerin as part of their chemical makeup (both animal and vegetable fats contain from 7% – 13% glycerine). When the fats and lye interact, soap is formed, and the glycerin is left out as a “byproduct”. But, while it’s chemically separate, it’s still blended into the soap mix.

While a cold process soapmaker would simply pour into the molds at this stage, a commercial soapmaker will add salt. The salt causes the soap to curdle and float to the top. After skimming off the soap, they are left with glycerin (and lots of “impurities” like partially dissolved soap, extra salt, etc.). They then separate the glycerin out by distilling it. Finally, they de-colorize the glycerin by filtering it through charcoal, or by using some other bleaching method.

Glycerin has lots of uses besides being used to make nitroglycerin (note: glycerin is not an explosive substance by itself. It has to be turned into nitroglycerin before it becomes explosive, so it’s safe to work with in your kitchen). Some uses for glycerin include: conserving preserved fruit, as a base for lotions, to prevent freezing in hydraulic jacks, to lubricate molds, in some printing inks, in cake and candy making, and (because it has an antiseptic quality) sometimes to preserve scientific specimens in jars in your high school biology lab.

Glycerin is also used to make clear soaps. Highly glycerinated clear soaps contain about 15% – 20% pure glycerin. Known as “Melt and Pour” soaps, these soaps are very easy for the hobbyist to work with. They melt at about 160 degrees fahrenheit, and solidify fairly rapidly. Because of their high glycerin content, the soaps are very moisturizing to the skin. Unfortunately, this high glycerin content also means that the soaps will dissolve more rapidly in water than soaps with less glycerin, and that if the bar of soap is left exposed to air, it will attract moisture and “glisten” with beads of ambient moisture.

These downsides, however are more than compensated by the emollient, skin loving and gentle nature of this soap which is especially good for tender skin and children.

(1) The pure chemical product is called Glycerol (which shows that it is an alcohol), while the impure commercial product is called Glycerin. This is a technical complexity, so for this article, I’m sticking to the more familiar term, Glycerin.

13 Responses to What Is Glycerin? | Glycerol

I bought some small peppermint patties and after eating two of them,I began violently ill in the night vomiting which tasted and foamed like glycerin or soap! What I vomited was foammy and seem to take the skin right off my throat…I could hardly swallow and my throat was full of saliva! I tried to cough but was unable to do so! After taking pepto bismal and breathing moist air thur a wet washrag it finally begin to feel better! Do they put glycerin in candy and why?

I recently bought a gluten-free cookbook and some of the recipes call for glycerin. Is there a difference between the soap glycerin and that used for cooking? Where would I buy cooking glycerin? What does it do in the baking process and is there something else that could be used instead?

What is lye, where can it be bought so we can make our own glycerin?
Great article
I’ve got skin issues and have been using awesome products without petro-chemicals. Now I find they contain palm oil derivatives, so I’ve been thinking I mite have to make my own! Starting to feel without hope, then I came across this easy to understand article. It may all be a bit beyond my capabilities, but, I have a resource~point of reference here, so I am no longer without hope entirely. Thanks!

if you want to make lye at home, you take wood ash (preferably pecan, apple, peach or cherry woods- burn them to ash) place in a container with small hole in bottom. place this container into a larger container and moisten the ash (you don’t want to bath the ash, just get it wet enough so that the water will filter down through the ash and drip out the bottom) it can take a while for the water to filter through all the ash, the liquid that comes out the bottom is lye.
make sure to use filtered or distilled water and make sure to use lye safe containers.
the resulting lye will have to be contentrated and is also a brownish color. there are ways to ‘clean’ the lye but i don’t know of any.
or you can by lye at the hardware stores normally marked for drain cleaning. some still carry it but many no longer do as meth makers tend to uses it to make drugs as well (this is what i was told as to why lye is no longer sold in some stores such as lowes or home depot and such.)